Historically, more lighting has been purchased based on the

• A. Wattage of the bulb
• B. Lumens of the bulb
• C. Lifespan of the bulb
• D. Color rendering index of the bulb

Answer: (A)

Historically, people bought lighting based on wattage because wattage was the practical stand-in for brightness in the era of incandescent bulbs. Higher wattage meant more energy was used, which people interpreted as more light output in real life, so retailers and consumers used wattage as the simple, familiar gauge of how bright a bulb would be. Lumen rating, which measures actual light output, wasn’t the standard reference at the time, even though it’s a more precise way to compare brightness. Lifespan and color rendering index measure how long a bulb lasts and how colors appear under the light, respectively, but they don’t tell you how bright the light is, so they weren’t the basis for purchasing decisions historically.